A hypertensive emergency is very high blood pressure with potentially life-threatening symptoms and signs of acute damage to one or more organ systems (especially brain, eyes, heart, aorta, or kidneys).

[7] The eyes may show bleeding in the retina, an exudate, cotton-wool spots, scattered splinter hemorrhages, or swelling of the optic disc called papilledema.

[8] Other common causes of hypertensive crises are autonomic hyperactivity such as pheochromocytoma, collagen-vascular diseases, drug use particularly stimulants, cocaine and amphetamines and their substituted analogues, monoamine oxidase inhibitors or food-drug interactions, spinal cord disorders, glomerulonephritis, head trauma, neoplasias, preeclampsia and eclampsia, hyperthyroidism and renovascular hypertension.

Failure of normal autoregulation and an abrupt rise in systemic vascular resistance are typical initial components of the disease process.

[6] If the process is not stopped, homeostatic failure begins, leading to loss of cerebral and local autoregulation, organ system ischemia and dysfunction, and myocardial infarction.

Hypertensives also have an increased cerebrovascular resistance which puts them at greater risk of developing cerebral ischemia if the blood flow decreases into a normotensive range.

Coronary perfusion pressures are decreased by these factors, which also increase myocardial oxygen consumption, possibly leading to left ventricular hypertrophy.

[7] If blood pressure is lowered aggressively, patients are at increased risk of complications including stroke, blindness, or kidney failure.

Physicians will attempt to identify a cause of the patient's hypertension, including chest radiograph, serum laboratory studies evaluating kidney function, urinalysis, as that will alter the treatment approach for a more patient-directed regimen.

Medications include labetalol, nicardipine, hydralazine, sodium nitroprusside, esmolol, nifedipine, minoxidil, isradipine, clonidine, and chlorpromazine.

Nicardipine, Nifedipine, and Isradipine are calcium channel blockers that work to decrease systemic vascular resistance and subsequently lower blood pressure.

Hydralazine and Sodium nitroprusside are systemic vasodilators, thereby reducing afterload, however can be found to have reflex tachycardia, making them likely second or third line choices.

Individuals with a history of chronic hypertension may not tolerate a "normal" blood pressure, and can therefore present symptomatically with hypotension, including fatigue, light-headedness, nausea, vomiting, or syncope.

[11] The morbidity and mortality of hypertensive emergencies depend on the extent of end-organ dysfunction at the time of presentation and the degree to which blood pressure is controlled afterward.

With good blood pressure control and medication compliance, the 5-year survival rate of patients with hypertensive crises approaches 55%.

Some examples of neurological damage include hypertensive encephalopathy, cerebral vascular accident/cerebral infarction, subarachnoid hemorrhage, and intracranial bleeding.